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Utility API

There is a newer version: 10.1.5

package com.peterphi.std.system.exec;

import java.io.IOException;
import java.io.StringWriter;
import java.util.List;

/**
 * A process tracker that reads stdout and stderr into Strings
 */
public class Execed extends AbstractProcessTracker
{
	// Outputs
	final StringWriter stdout_content = new StringWriter();
	final StringWriter stderr_content;

	final Thread stdoutRead;
	final Thread stderrRead;


	public static Execed spawn(Exec e) throws IOException
	{
		ProcessBuilder pb = e.getProcessBuilder();

		return new Execed(e.cmd, pb.start(), pb.redirectErrorStream());
	}


	protected Execed(List cmd, Process p, boolean combinedOutput)
	{
		super(cmd, p, combinedOutput);

		if (combinedOutput)
		{
			stderr_content = null;

			stdoutRead = copy(p.getInputStream(), stdout_content);
			stderrRead = null;
		}
		else
		{
			stderr_content = new StringWriter();

			stdoutRead = copy(p.getInputStream(), stdout_content);
			stderrRead = copy(p.getErrorStream(), stderr_content);
		}
	}


	public String getStandardOut()
	{
		this.stdout_content.flush();

		return this.stdout_content.toString();
	}


	public String getStandardError()
	{
		if (stderr_content == null)
			return null;
		else
			return this.stderr_content.toString();
	}


	@Override
	public boolean isFinished()
	{
		return super.isFinished() && !stdoutRead.isAlive();
	}


	@Override
	protected boolean isStillReadingOutput()
	{
		if (stdoutRead != null && stdoutRead.isAlive())
			return true;
		if (stderrRead != null && stderrRead.isAlive())
			return true;

		return false; // no read threads active
	}


	@Override
	public void discardOutput()
	{
		throw new RuntimeException("SimpleOutputGrabber cannot discard output!");
	}
}